1. Field of the Invention
The present invention relates to a thin film magnetic head for recording used in, for example, a floating magnetic head. In particular, the present invention relates to a thin film magnetic head and a method for manufacturing the same, wherein first coil pieces and second coil pieces provided one above the other with a magnetic layer therebetween are electrically connected to each other with reliability and with ease, and the magnetic layer can be provided on a flattened surface.
2. Description of the Related Art
Each of known documents, Japanese Unexamined Patent Application Publication No. 11-273028, Japanese Unexamined Patent Application Publication No. 2000-311311, Japanese Unexamined Patent Application Publication No. 2002-170205, and U.S. Pat. No. 6,335,846 B1, discloses a configuration of a coil layer wound in a toroidal shape around a core constituting an inductive head (recording head).
Preferably, the above-described coil layer is allowed to have a toroidal shape in order to make full use of a three-dimensional space around the above-described core and, thereby, it is expected that miniaturization of the inductive head can be realized and the magnetization efficiency becomes excellent.
However, the toroidal coil structures described in the above-described patent documents have the following problems.
Each of these documents describes that lower coil layers provided under a core layer (for example, an upper core layer) and upper coil layers provided on the above-described core layer are electrically connected via connection layers, and this connection layer is formed by, for example, digging a through hole connected to the above-described lower coil layer in an insulating layer provided on the lower coil layer and, thereafter, growing a layer of plating from this through hole.
However, a plurality of lower coil layers, described above, are densely provided in a narrow region, and the two-dimensional size of the above-described connection layer is smaller than the width of the lower coil layer in each document. Consequently, it is practically difficult to form the through hole connected to each lower coil layer if significantly high-precise etching technique is not available. Furthermore, the above-described etching has a high risk of damaging the lower coil layer.
With respect to the growth of the connection layer by plating from the above-described through hole, if the above-described through hole is not properly dug to reach the top surface of the lower coil layer, growth of plating cannot be appropriately performed. If formation of the above-described connection layer by plating is terminated, for example, midway through the above-described through hole, electrical connection to the upper coil layer tends to become unstable.
The top surface of the insulating layer provided on the above-described lower coil layer is undulated due to, for example, height difference between the above-described lower coil layer and the lower core layer. Since the upper core layer must be formed on the top surface of the above-described insulation layer having such undulations, the above-described upper core layer cannot be patterned into a predetermined shape. In addition, it is essentially difficult to form the above-described through hole having a predetermined shape in the insulating layer having undulations. Furthermore, since the upper coil layers provided on the above-described upper core layer with another insulating layer therebetween are also provided on a surface having undulations, electrical connection between the above-described upper coil layers and the lower coil layers via the connection layers tends to become unstable.